1. Field of the Invention
This invention relates generally to elect switches having no moving contacts, and more specifically, to such electronic switches utilizing a switching signal generated by deformation of a piezoelectric material.
2. Description of the Prior Art
Contactless piezoelectric switches are known in the prior art. Typically, such switches employ a deformable face or surface, and a thin body of piezoelectric material arranged such that a deforming force is transmitted from the face or surface to the piezoelectric material, thus causing the material to generate an electrical signal. Electrodes are employed in conjunction with the body of piezoelectric material so that the electrical signal may be communicated to, for example, switch circuitry. Thus, when the deformable face is pressed by the user, the piezoelectric material generates an electrical signal and activates the switching circuit. Such switches are disclosed in, for example, U.S. Pat. Nos. 3,339,104 and 4,618,797.
Such contactless switches have inherent advantages over conventional switches with moving parts in that they can be made vandal-proof and are much less sensitive to environmental degradation. They have no moving parts or electrical contacts to wear out, and produce no electrical arc or electromagnetic interference, a great benefit in explosive or sensitive electronic environments.
However, the piezoelectric contactless switches of the prior art suffer from certain disadvantages. They are designed to accommodate piezoelectric bodies, which are typically bonded to a support member, and which must be fit to close tolerances, thus necessitating expensive shaping operations which can damage this delicate material. Furthermore, since the piezoelectric chips used in the prior art switches must be custom fitted, the devices cannot employ relatively inexpensive piezoelectric disks which are available in standard sizes and configurations.
It would be desirable to provide a contactless, piezoelectric switch assembly which is easy to assemble, inexpensive to manufacture and which employs standard components. It would further be advantageous to provide such a switch which is both durable and reliable.